Patent Document 1, for example, discloses a multi-layered blow molded plastic bottle utilizing a recycled material for the middle layer. Patent Document 2 discloses a die for use in blow molding multi-layered bottles, such as the one described in Patent Document 1. Traditionally, it is a widespread practice, from cost-reduction and resources-saving points of view, to collect flash and defective products occurring from production processes and to utilize regenerated materials or so-called recycled materials as the materials for the middle layer of multi-layered containers.    [Patent Document 1] Published patent application JP1993-338638    [Patent Document 2] Published patent application JP1998-128836